This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Correcting for imbalances in crankshafts or other rotating members has traditionally been somewhat of a trial and error process. Although it is possible to measure the overall imbalance of a rotating member, correcting for this imbalance by adding or subtracting weight at offsetting locations can be difficult because often there may be more than one solution for where to add or subtract material. Ideally, one would like to find an optimal solution that requires minimal invasive adding or subtracting of material. However, in conventional systems finding this optimal solution has proven difficult.
In the case of a crankshaft, for example, there are multiple sites radially disposed along the longitudinal axis. Each of these sites can potentially be used as drill sites from which to remove weight in order to offset an imbalance. However, a machinist has only his personal judgment regarding where to drill and how deep. The goal, of course, is to remove material to counteract the measured imbalance.
This is not as easy as it might appear at first blush. Because the crankshaft has a significant longitudinal dimension, drilling to offset a static imbalance can introduce dynamic imbalances. This is because a crankshaft, like other elongated rotating members, can exhibit vibration in multiple modes, just as a plucked string can vibrate at the primary frequency and also at integer multiples of the primary frequency. Thus drilling to remove the primary mode of imbalance or vibration could possibly introduce unwanted vibrations at higher order modes.
The disclosed weight splitting control system addresses solves the aforementioned difficulties in finding the optimal locations(s) for removing or adding material. Although drilling to remove material is described here, it will be understood that the solutions generated by the system can also be used to indicate where material may be added to achieve balance. Also, while drilling to remove material is disclosed here, other methods of removing material are also possible, including abrading, ablation, cutting, laser cutting, chemical etching and the like.
The disclosed weight splitting control system employs an apparatus for reducing imbalance in an elongated rotating workpiece, including a measuring machine receptive of the workpiece that outputs imbalance data for the workpiece. A solution processor having an associated memory is programmed to receive the imbalance data.
The associated memory is programmed according to a predefined model data structure to store the imbalance data and also store data indicative of the geometry of the workpiece, where the model data structure stores workpiece geometry data representing the location of at least one workpiece modification site, referenced to at least one predetermined reference frame.
The solution processor is programmed to execute a solver program that seeks at least one solution to reduce the imbalance, using the model data structure as solver constraints. The solution processor outputs at least one solution as imbalance reduction data representing the location of at least one workpiece modification site together with a datum indicative of a weight to be added to or removed from the workpiece at the modification site.
A workpiece modification machine receptive of the workpiece and having a workpiece modification processor uses the output of the solution processor to control a machine that physically modifies the workpiece to reduce imbalance.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.